Well the surprises just keeps mounting. After shocking everyone with the announcement that Ubuntu 11.04 will have Unity on the desktop instead of GNOME Shell, Mark Shuttleworth announced another possibly bigger change - Unity is going to use Wayland display server instead of X. This will not be implemented in Ubuntu 11.04 though

This is what Shuttleworth wrote:

The next major transition for Unity will be to deliver it on Wayland, the OpenGL-based display management system. We’d like to embrace Wayland early, as much of the work we’re doing on uTouch and other input systems will be relevant for Wayland and it’s an area we can make a useful contribution to the project.

Compared to X, Wayland is a very young project. It was started by Kristian Høgsberg, who said that the aim of Wayland is "every frame is perfect, by which I mean that applications will be able to control the rendering enough that we'll never see tearing, lag, redrawing or flicker."

Regarding the reason for the switch, Shuttleworth said that X is not setup to deliver the super-smooth graphics and effects which he has envisioned for Ubuntu. This is what he wrote:

But we don’t believe X is setup to deliver the user experience we want, with super-smooth graphics and effects. I understand that it’s *possible* to get amazing results with X, but it’s extremely hard, and isn’t going to get easier. Some of the core goals of X make it harder to achieve these user experiences on X than on native GL, we’re choosing to prioritize the quality of experience over those original values, like network transparency.

This is certainly a very interesting direction that Ubuntu is taking. It should not only help Ubuntu but also give a big boost to the Wayland project. The Wayland project has so much potential and this backing from Canonical should do the project a lot of good.

X will however stay for the next release, Ubuntu 11.04, though and possible some more releases after that. As Shuttleworth mentioned, six month is an unrealistic period for something like this. We may see some signs of Wayland in Ubuntu in about a year (Ubuntu 11.10). However moving the entire ecosystem to Wayland will take several years.